LTC1860/LTC1861
µPower,
12-Bit, 250ksps
1- and 2-Channel ADCs in MSOP
FEATURES
s
s
s
s
DESCRIPTIO
s
s
s
s
s
12-Bit 250ksps ADCs in MSOP Package
Single 5V Supply
Low Supply Current: 850µA (Typ)
Auto Shutdown Reduces Supply Current
to 2µA at 1ksps
True Differential Inputs
1-Channel (LTC1860) or 2-Channel (LTC1861)
Versions
SPI/MICROWIRE
TM
Compatible Serial I/O
High Speed Upgrade to LTC1286/LTC1298
Pin Compatible with 16-Bit LTC1864/LTC1865
The LTC
®
1860/LTC1861 are 12-bit A/D converters that are
offered in MSOP and SO-8 packages and operate on a
single 5V supply. At 250ksps, the supply current is only
850µA. The supply current drops at lower speeds because
the LTC1860/LTC1861 automatically power down to a
typical supply current of 1nA between conversions. These
12-bit switched capacitor successive approximation ADCs
include sample-and-holds. The LTC1860 has a differential
analog input with an adjustable reference pin. The LTC1861
offers a software-selectable 2-channel MUX and an ad-
justable reference pin on the MSOP version.
The 3-wire, serial I/O, MSOP or SO-8 package and
extremely high sample rate-to-power ratio make these
ADCs ideal choices for compact, low power, high speed
systems.
These ADCs can be used in ratiometric applications or with
external references. The high impedance analog inputs
and the ability to operate with reduced spans down to 1V
full scale, allow direct connection to signal sources in
many applications, eliminating the need for external gain
stages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
APPLICATIO S
s
s
s
s
High Speed Data Acquisition
Portable or Compact Instrumentation
Low Power Battery-Operated Instrumentation
Isolated and/or Remote Data Acquisition
TYPICAL APPLICATIO
1µF
Supply Current vs Sampling Frequency
Single 5V Supply, 250ksps, 12-Bit Sampling ADC
1000
SUPPLY CURRENT (µA)
5V
100
LTC1860
1
2
ANALOG INPUT
0V TO 5V
3
4
V
REF
IN
+
IN
–
GND
V
CC
SCK
SDO
CONV
8
7
6
5
1860 TA01
10
1
SERIAL DATA LINK TO
ASIC, PLD, MPU, DSP
OR SHIFT REGISTERS
0.1
0.01
0.01
0.1
10
100
1
SAMPLING FREQUENCY (kHz)
U
1000
1860 TA02
U
U
18601f
1
LTC1860/LTC1861
ABSOLUTE
AXI U
RATI GS
Supply Voltage (V
CC
) ................................................. 7V
Ground Voltage Difference
AGND, DGND LTC1861 MSOP Package ...........
±0.3V
Analog Input .................... (GND – 0.3V) to (V
CC
+ 0.3V)
Digital Input ..................................... (GND – 0.3V) to 7V
Digital Output .................. (GND – 0.3V) to (V
CC
+ 0.3V)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
REF
IN
+
IN¯
GND
1
2
3
4
8
7
6
5
V
CC
SCK
SDO
CONV
ORDER PART
NUMBER
LTC1860CMS8
LTC1860IMS8
MS8 PART MARKING
LTWR
LTWS
ORDER PART
NUMBER
LTC1860CS8
LTC1860IS8
S8 PART MARKING
1860
1860I
CONV
CH0
CH1
AGND
DGND
1
2
3
4
5
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 210°C/W
TOP VIEW
V
REF
1
IN
+
2
IN
–
8 V
CC
7 SCK
6 SDO
5 CONV
3
GND 4
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 175°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
CO VERTER A D
PARAMETER
Resolution
No Missing Codes Resolution
INL
Transition Noise
Gain Error
Offset Error
Input Differential Voltage Range
Absolute Input Range
V
REF
Input Range
Analog Input Leakage Current
C
IN
Input Capacitance
ULTIPLEXER CHARACTERISTICS
CONDITIONS
q
q
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
CC
= 5V, V
REF
= 5V, f
SCK
= f
SCK(MAX)
as defined in Recommended Operating Conditions, unless otherwise noted.
MIN
12
12
±1
0.07
q
(Note 3)
LTC1860 SO-8 and MSOP, LTC1861 MSOP
LTC1861 SO-8
V
IN
= IN
+
– IN
–
IN
+
Input
IN
–
Input
LTC1860 S0-8 and MSOP, LTC1861 MSOP
(Note 4)
In Sample Mode
During Conversion
2
U
U
W
W W
U
W U
W
(Notes 1, 2)
Power Dissipation .............................................. 400mW
Operating Temperature Range
LTC1860C/LTC1861C ............................. 0°C to 70°C
LTC1860I/LTC1861I .......................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
10
9
8
7
6
V
REF
V
CC
SCK
SDO
SDI
ORDER PART
NUMBER
LTC1861CMS
LTC1861IMS
MS PART MARKING
LTWT
LTWU
ORDER PART
NUMBER
LTC1861CS8
LTC1861IS8
S8 PART MARKING
1861
1861I
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 210°C/W
TOP VIEW
CONV 1
CH0 2
CH1 3
GND 4
8 V
CC
7 SCK
6 SDO
5 SDI
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 175°C/W
U
TYP
MAX
UNITS
Bits
Bits
LSB
LSB
RMS
mV
mV
mV
V
V
V
V
µA
pF
pF
18601f
q
±20
±2
±3
0
– 0.05
– 0.05
1
±5
±7
V
REF
V
CC
+ 0.05
V
CC
/2
V
CC
±1
12
5
q
q
q
q
LTC1860/LTC1861
DY A IC ACCURACY
T
A
= 25°C. V
CC
= 5V, f
SAMPLE
= 250kHz, unless otherwise specified.
SYMBOL PARAMETER
SNR
THD
Signal-to-Noise Ratio
100kHz Input Signal
Total Hamonic Distortion Up to 5th Harmonic 100kHz Input Signal
Full Power Bandwidth
Full Linear Bandwidth
S/(N + D)
≥
68dB
S/(N + D) Signal-to-Noise Plus Distortion Ratio
CONDITIONS
MIN
TYP
72
71
77
20
125
MAX
UNITS
dB
dB
dB
MHz
kHz
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
V
IH
V
IL
I
IH
I
IL
V
OH
V
OL
I
OZ
I
SOURCE
I
SINK
I
REF
I
CC
P
D
High Level Input Voltage
Low Level Input Voltage
High Level Input Current
Low Level Input Current
High Level Output Voltage
Low Level Output Voltage
Hi-Z Output Leakage
Output Source Current
Output Sink Current
CONDITIONS
V
CC
= 5.25V
V
CC
= 4.75V
V
IN
= V
CC
V
IN
= 0V
V
CC
= 4.75V, I
O
= 10µA
V
CC
= 4.75V, I
O
= 360µA
V
CC
= 4.75V, I
O
= 1.6mA
CONV = V
CC
V
OUT
= 0V
V
OUT
= V
CC
The
q
denotes specifications which apply
over the full operating temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 5V, V
REF
= 5V, unless otherwise noted.
MIN
q
q
q
q
q
q
q
q
Reference Current (LTC1860 SO-8, MSOP and CONV = V
CC
LTC1861 MSOP)
f
SMPL
= f
SMPL(MAX)
Supply Current
Power Dissipation
CONV = V
CC
After Conversion
f
SMPL
= f
SMPL(MAX)
f
SMPL
= f
SMPL(MAX)
RECO
V
CC
f
SCK
t
CYC
t
SMPL
t
suCONV
t
hDI
t
suDI
t
WHCLK
t
WLCLK
t
WHCONV
t
WLCONV
t
hCONV
full operating temperature range, otherwise specifications are T
A
= 25°C.
SYMBOL PARAMETER
Supply Voltage
Clock Frequency
Total Cycle Time
Analog Input Sampling Time
Setup Time CONV↓ Before First SCK↑,
(See Figure 1)
Holdtime SDI After SCK↑
Setup Time SDI Stable Before SCK↑
SCK High Time
SCK Low Time
CONV High Time Between Data
Transfer Cycles
CONV Low Time During Data Transfer
Hold Time CONV Low After Last SCK↑
LTC1861
LTC1861
f
SCK
= f
SCK(MAX)
f
SCK
= f
SCK(MAX)
LTC1860
LTC1861
CONDITIONS
E DED OPERATI G CO DITIO S
U
U
U
U WW
U
W U
TYP
MAX
0.8
2.5
– 2.5
UNITS
V
V
µA
µA
V
V
2.4
4.5
2.4
4.74
4.72
0.4
±3
– 25
20
V
µA
mA
mA
q
q
q
q
0.001
0.05
0.001
0.85
4.25
3
0.1
3
1.3
µA
mA
µA
mA
mW
The
q
denotes specifications which apply over the
MIN
4.75
q
TYP
MAX
5.25
20
UNITS
V
MHz
µs
SCK
SCK
ns
ns
ns
1/f
SCK
1/f
SCK
µs
SCK
ns
DC
12 • SCK + t
CONV
12
10
30
15
15
40%
40%
t
CONV
12
13
18601f
3
LTC1860/LTC1861
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are T
A
= 25°C. V
CC
= 5V, V
REF
= 5V, f
SCK
= f
SCK(MAX)
as defined in Recommended Operating
Conditions, unless otherwise noted.
SYMBOL
t
CONV
t
dDO
t
dis
t
en
t
hDO
t
r
t
f
PARAMETER
Conversion Time (See Figure 1)
Delay Time, SCK↓ to SDO Data Valid
Delay Time, CONV↑ to SDO Hi-Z
Delay Time, CONV↓ to SDO Enabled
Time Output Data Remains
Valid After SCK↓
SDO Rise Time
SDO Fall Time
C
LOAD
= 20pF
C
LOAD
= 20pF
C
LOAD
= 20pF
C
LOAD
= 20pF
C
LOAD
= 20pF
q
q
q
q
TI I G CHARACTERISTICS
f
SMPL(MAX)
Maximum Sampling Frequency
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
All voltage values are with respect to GND.
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Sampling
Frequency
1000
CONV LOW = 800ns
T
A
= 25°C
V
CC
= 5V
1000
100
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
SLEEP CURRENT (nA)
10
1
0.1
0.01
0.01
0.1
10
100
1.0
SAMPLING FREQUENCY (kHz)
4
U W
UW
CONDITIONS
q
q
MIN
250
TYP
2.75
15
30
30
MAX
3.2
20
25
60
60
UNITS
µs
kHz
ns
ns
ns
ns
ns
ns
ns
5
10
8
4
Note 3:
Integral nonlinearity is defined as deviation of a code from a
straight line passing through the actual endpoints of the transfer curve.
The deviation is measured from the center of the quantization band.
Note 4:
Channel leakage current is measured while the part is in sample
mode.
Supply Current vs Temperature
1000
900
800
800
700
600
500
400
300
200
100
Sleep Current vs Temperature
CONV = V
CC
= 5V
600
400
CONV HIGH = 3.2µS
f
SMPL
= 250kHz
V
CC
= 5V
V
REF
= 5V
–25
50
0
75
25
TEMPERATURE (°C)
100
125
200
1000
1860/61 G01
0
–50
0
–50
–25
50
0
75
25
TEMPERATURE (°C)
100
125
1860/61 G02
1860/61 G03
18601f
LTC1860/LTC1861
TYPICAL PERFOR A CE CHARACTERISTICS
Reference Current vs
Sample Rate
60
50
CONV IS LOW FOR 800ns
T
A
= 25°C
V
CC
= 5V
V
REF
= 5V
REFERENCE CURRENT (µA)
REFERENCE CURRENT (µA)
40
30
20
10
0
I
REF
(µA)
0
50
100
150
200
SAMPLE RATE (kHz)
Typical INL Curve
1.0
T
A
= 25°C
V
CC
= 5V
V
REF
= 5V
1.0
ANALOG INPUT LEAKAGE (nA)
DNL EOC ERROR (LSBs)
INL COC ERROR (LSBs)
0.5
0
–0.5
–1.0
0
512 1024 1536 2048 2560 3072 3584 4096
CODE
1860/61 G07
Change in Offset Error vs
Reference Voltage
5
4
CHANGE IN OFFSET ERROR (LSB)
2
1
0
–1
–2
–3
–4
–5
0
1
3
4
2
REFERENCE VOLTAGE (V)
5
1860/61 G10
CHANGE IN OFFSET (LSB)
3
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–50
–25
50
0
75
25
TEMPERATURE (°C)
100
125
CHANGE IN GAIN ERROR (LSB)
U W
1860/61 G04
Reference Current vs
Temperature
55
f
S
= 250kHz
54 V
CC
= 5V
= 5V
V
53
REF
52
51
50
49
48
47
46
250
Reference Current vs
Reference Voltage
60
f
S
= 250kHz
T
A
= 25°C
50 V
CC
= 5V
40
30
20
10
0
45
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
0
1
2
3
V
REF
(V)
4
5
1860/61 G06
1860/61 G05
Typical DNL Curve
T
A
= 25°C
V
CC
= 5V
V
REF
= 5V
100
Analog Input Leakage vs
Temperature
V
CC
= 5V
V
REF
= 5V
CONV = 0V
0.5
75
0
50
–0.5
25
–1.0
0
512 1024 1536 2048 2560 3072 3584 4096
CODE
1860/61 G07
0
–50 –25
0
25
50
75
100
125
TEMPERATURE (°C)
1860/61 G09
Change in Offset vs Temperature
T
A
= 25°C
V
CC
= 5V
1.0
0.8
V
CC
= 5V
5
Change in Gain Error vs
Reference Voltage
V
CC
= 5V
4 T
A
= 25°C
3
2
1
0
–1
–2
–3
–4
–5
0
1
4
2
3
REFERENCE VOLTAGE(V)
5
1860/61 G12
1860/61 G11
18601f
5
